This disclosure relates generally to vascular access devices and associated methods. More specifically, this disclosure discusses a cannula capture mechanism that is configured to capture a cannula tip in a manner that locks the cannula in a shielded position. The cannula capture mechanism can be used with catheter assemblies.
Generally, vascular access devices are used for communicating fluid with the vascular system of patients. For example, catheters are used for infusing fluid (e.g., saline solution, medicaments, and/or total parenteral nutrition) into a patient, withdrawing fluids (e.g., blood) from a patient, and/or monitoring various parameters of the patient's vascular system.
Intravenous (IV) catheter assemblies are among the various types of vascular access devices. Over-the-needle peripheral IV catheters are a common IV catheter configuration. As its name implies, an over-the-needle catheter is mounted over an introducer needle having a sharp distal tip. The introducer needle is generally a hypodermic needle coupled to a needle assembly to help guide the needle and to facilitate its cooperation with the catheter. At least the inner surface of the distal portion of the catheter tightly engages the outer surface of the needle to prevent peelback of the catheter and, thereby, facilitate insertion of the catheter into the blood vessel. The catheter and the introducer needle are often assembled so that the distal tip of the introducer needle extends beyond the distal tip of the catheter. Moreover, the catheter and needle are often assembled so that, during insertion, the bevel of the needle faces up, away from the patient's skin. The catheter and introducer needle are generally inserted at a shallow angle through the patient's skin into a blood vessel.
In order to verify proper placement of the needle and/or catheter in the blood vessel, the operator generally confirms that there is “flashback” of blood into a flashback chamber associated with the needle assembly. Flashback generally entails the appearance of a small amount of blood, which is visible within the needle assembly or between the needle and the catheter. Once proper placement of the distal tip of the catheter into the blood vessel is confirmed, the operator may apply pressure to the blood vessel by pressing down on the patient's skin over the blood vessel, distal to the introducer needle and the catheter. This finger pressure momentarily occludes the vessel, minimizing further blood flow through the introducer needle and the catheter.
The operator may then withdraw the introducer needle from the catheter. The needle may be withdrawn into a needle tip cover or needle cover that extends over the needle's tip and prevents accidental needle sticks. In general, a needle tip cover includes a casing, sleeve, or other similar device that is designed to trap/capture the needle tip when the introducer needle is withdrawn from the catheter and the patient. After the needle is withdrawn, the catheter is left in place to provide intravenous access to the patient.
The separation of the introducer needle assembly from the catheter portions of the catheter assembly presents numerous potential hazards to the operators and others in the area. As indicated above, there is a risk of accidental needle sticks if the needle tip is not secured properly in a needle tip shield. Additionally, because the needle has been in contact with blood in the patient's vasculature, blood is often present on the needle's exterior as well as inside the lumen of the needle. As the needle is withdrawn from the catheter, there is a risk that this blood will drip from the needle tip or come into contact with other surfaces to expose people and equipment to blood. Additionally, it has been observed that withdrawing a needle from a catheter assembly often imparts energy to the parts of the needle assembly. For instance, during needle withdrawal, bending forces can be applied (either unintentionally or intentionally) to the needle. Such energy has been observed to cause blood to splatter or spray from the needle when the needle vibrates and shakes as it becomes free from the catheter assembly and releases the stored energy.
The present disclosure discusses a cannula capture mechanism that allows a needle to be retracted from an unshielded position to a shielded position in which the cannula feature is trapped. Accordingly, the described capture mechanism is configured to lock the needle in the shielded position to significantly limit or prevent accidental sticks and blood exposure after the needle is withdrawn from a catheter assembly.